Coupled column liquid chromatography for the rapid determination of N-methylcarbamates and some of their main metabolites in water

A sensitive and selective coupled-column liquid chromatography (LC-LC) meth od was developed for the trace level determination of some N-methylcarbamat es and some of their main metabolites as aldicarb, aldicarb-sulphoxide, ald icarb-sulphone, carbofuran and 3-hydroxicarbofuran in drinking and ground w aters. The limit of determination can be reduced to 0.1 mu g.L-1 by solid p hase extraction with a subsequent evaporation step. Environmental samples s piked at 0.1 mu g.L-1 were preconcentrated off-line with graphite carbon an d then analyzed by LC-LC with UV detection yielding average recoveries betw een 81-109 % (n = 5) with RSD between 5-9 %. The overall procedure allowed a sample throughput of up to 30 samples per day.